Dynamics Of Soil Enzyme And Nutrients Of Alpine Meadows Under Different Degraded Degrees In Eastern Qilian Mountains

The alpine meadows in Eastern Qilian Mountains under different degraded degrees (light degradation, heavy degradation and over degradation) were selected to study the seasonal change and the impacts of different degraded degrees on activities of soil enzymes (urease, cellulose and peroxidase) and soil nutrients (total N, available N, total P, available P and organic matter).The result showed that the activity of urease in light and heavy degradation meadow was the highest in spring and the lowest in fall. The change of activity of urease among spring, summer and fall was not significant. The activity of neutral phosphatase was the highest in summer and the lowest in spring. From May to July the amplitude of activity of neutral phosphatase reached to 1139.13%. The activity of cellulose was the lowest in summer. The variation of activity of cellulose between July and September was close to that between May and July. The activity of peroxidase in over and heavy degradation meadows was the highest in fall and the lowest in spring. From July to September, the activity of peroxidase in heavy degradation meadow was higher than over degradation meadow.Based on the statistical analysis, the difference of cellulose activities between light degradation meadow and other degradation meadows was extremely significant. The impact of light and over degradation on neutral phosphatase was extremely remarkable. The impact of different degrees of degradation on activities of urease and peroxidase varied.Seasonal variation patterns of soil organic matter, total P, available P and total N were similar. Their contents were the highest in fall and they increased by 27.12%, 8.11%, 15.12% and 13.77% respectively compared with those in Spring.The degradation showed remarkable impact on contents of soil organic matter, total P, available P and total N. The content of soil organic matter, total P and available P decreased with the degradation degree of meadow. However, the content of available N under different degradation showed the following order: heavy degradation > light degradation > over degradation.